Carmike 10, Cinemark 16, Tinseltown Few filmmakers have the unique ability to tickle viewers' funny bones while tugging on their heartstrings. But with the release of Knocked Up, his second feature film, writer-director Judd Apatow has proven not only that he can do so, but that he can do so without breaking a sweat.

When Apatow's The 40-Year-Old Virgin became the sleeper hit of 2005, Hollywood took note: A hungry demographic for adult comedies actually did exist. Now, two years later and in a summer movie season pregnant with sequels and blockbuster adaptations, Knocked Up represents a landmark achievement for the genre.

On a particularly wild night, twentysomething slacker Ben Stone (Seth Rogen) meets Alison Scott (Katherine Heigl), a newly promoted on-air correspondent for E! Television. Although they look like members of different species, the two actually hit it off quite well and then, with the aid of some alcohol, drunken fumbling ensues.

The rest, as they say, is history. The next morning, as the lovebirds share an awkward breakfast out, Ben struggles to hide his ear-to-ear grin and Alison laments her mistake. And once she pays the bill, they agree to amicably part ways.

Several weeks later, though, Ben gets a dreaded phone call: Alison is pregnant. To say this throws Ben's world into disarray would be an understatement. Ben is possibly the least prepared person to raise a child. He still lives off a chump-change settlement he won after being run over in high school, and he and his friends plan to strike it rich with a celebrity-skin pornography Web site despite the fact that hundreds of such sites already exist.

Things get a bit more serious in the second act, though, as our Beauty and Beast try their relationship out for size. Although their getting-to-know-you shtick fails miserably as Ben takes some warming up to Alison starts seeing him for the sweet guy that he is. The rest of the film finds Ben struggling to come to terms with reality, impending fatherhood and the responsibilities it entails.

Thanks to Apatow's sentimental sensibilities, though, Knocked Up remains a delicate balance of heart and hilarity. For every genuinely touching moment like, for instance, when Alison takes Ben's hand as they shop for baby cribs there's a scene that ups the ante for gross-out humor. The inevitable birthing scene, which depicts the baby crowning, is among the most graphic visual gags ever committed to celluloid. It's as cringe-worthy and hysterical as Aunt Magda's breasts being exposed in There's Something About Mary.

Meanwhile, Rogen delivers an effortless performance that will undoubtedly earn the rotund Canadian comic comparisons to the late John Belushi. Without a doubt, his is the most accurate portrayal of post-collegiate malaise ever depicted on screen; he elevates Ben from a cinematic creation to a bona fide human being with anxieties and neuroses.

The only knocks Knocked Up merits are that it's a tad too long especially for a comedy and that one scene in particular, when the gang takes in a Cirque de Soleil show while on hallucinogenic mushrooms, feels forced and out of place.

But these are minor miscues, overshadowed by Apatow's otherwise stellar efforts throughout the film. Knocked Up is every bit a knockout. scene@csindy.com